Ulysses' trip

Latest post

A hand holding a Wacom pen with pen grip.

Oct 29, 2025, 23:18:50

Ever since I installed the pen holder grip on my #Wacom pen, the pain in my right thumb disappeared. Very nice.

Articles

Feb 3, 2023
手纸本

何为手纸本?
- Categories: literature
- Tags: from zhihu, literary composition, short story, chinese
Feb 3, 2023
Introducing bra–ket notation to math learners

Bra–ket notation is a good-looking notation! I am sad that it is not generally taught in math courses. Let me introduce it to you.
- Categories: math
- Tags: from zhihu, quantum mechanics
Feb 2, 2023
Even solutions to bound states in an odd number of $\delta$ potential wells

We try solving the even function solutions to the time-independent Schrödinger equation for the potential $V=-\alpha\sum_{j=-n}^n\delta(x-ja)$ such that $E<0$ (bound states).
- Categories: physics
- Tags: from zhihu, quantum mechanics
Feb 1, 2023
Defend our earth against aliens’ bullets!

The aliens intiated their attack to the earth! They shoot bullets with mass $m$ and speed $v$ from a far-awar planet. To defend, humans built a field $U=\alpha/r$ that can repel the bullets. What regions are safe? The answer turns out to be the interior of a circular paraboloid.
- Categories: physics
- Tags: calculus, classical mechanics, kepler problem, from zhihu
Jan 18, 2023
This is what will happen after you get a haircut

Denote the length distribution of one’s hair to be $f(l,t)$ , where $l$ is hair length, and $t$ is time. Considering that each hair may be lost naturally from time to time (there is a probability of $\lambda\,\mathrm dt$ for each hair to be lost within time range from $t$ to $t+\mathrm dt$ ) and then restart growing from zero length, how will the length distribution of hair evolve with time? It turns out that we may model it with a first-order PDE.
- Categories: math
- Tags: calculus, probability, pde
Jan 11, 2023
I want to invent a better way to read numbers

Reading numbers in English is a pain. I want to invent a better way to read numbers!
- Categories: language
- Tags: imagination
Dec 25, 2022
The longest all- $1$ substring of a random bit string

Given your probability of breaking the combo at each note, what is the probability distribution of your max combo in the rhythm game chart? I considered the problem seriously!
- Categories: math
- Tags: long paper, rhythm game, algorithm, probability
Dec 5, 2022
I made this, for the number of days in a week is prime

The number of days in a week is prime, so we cannot utilize weekly periods to help us remember periodical events unless the period is a multiple of 7. However, there may be something that we need to get reminded of which happens once per two days or three days. For example, I wash my hair once per two days and wash my clothes once per eight days. To solve the problem, I wrote a Ruby program to help remind me of those routines.
- Categories: programming
- Tags: selfhosting, linux, ruby
Nov 28, 2022
Using ntfy to warn me when my computer is discharging

I use udev and systemd to send a notification to my phone via ntfy automatically whenever my laptop is discharging.
- Categories: programming
- Tags: selfhosting, linux
Nov 20, 2022
How to construct mechanics in higher dimensions?

We can derive the equation of motion for mechanical systems in a Galileo universe with $\iota$ time dimensions and $\chi$ space dimensions by generalizing the principle of relativity and Hamilton’s principle.
- Categories: physics
- Tags: from zhihu, classical mechanics, imagination